Protesters snarled traffic in Jerusalem and another large religious enclave, crowded onto balconies in city squares, and waved posters decrying the court's decision and proclaiming the supremacy of religious law.

There were a few small scuffles, and a police officer emerged from one of them holding his eye, apparently slightly injured.

It was one of the largest protests in Jerusalem's history, and a stark reminder of the ultra-Orthodox minority's refusal to accept the authority of the state.

Also, the throngs of devout Jews showed to which extent the ultra-Orthodox live by their own rules, some of them archaic, while wielding disproportionate power in the modern state of Israel.

Parents of European, or Ashkenazi, descent at a girls' school in the West Bank settlement of Emanuel don't want their daughters to study with schoolgirls of Mideast and North African descent, known as Sephardim.

The Ashkenazi parents insist they aren't racist, but want to keep the classrooms segregated, as they have been for years, arguing that the families of the Sephardi girls aren't religious enough.

Israel's Supreme Court rejected that argument, and ruled that the 43 sets of parents who have defied the integration efforts by keeping their daughters from school were to be jailed on Thursday for two weeks.

Police spokesman Micky Rosenfeld said about 100,000 people converged in downtown Jerusalem in support of the Ashkenazi parents. An additional 20,000 demonstrated in the central city of Bnei Brak. He said 10,000 police were deployed.

Most of the demonstrators were men wearing the long beards and heavy black clothing typical among ultra-Orthodox Jews. "The Supreme Court is fascist," said one poster.

Esther Bark, 50, who has seven daughters, said the issue is keeping the girls away from the temptations of the modern world. "To suddenly put them in an open-minded place is not good for them," she said.

Sephardi religious leaders have not publicly criticized the demonstration or the Ashkenazi parents' conduct.

Nissim Zeev, a lawmaker from the Orthodox Sephardic political party Shas, said the issue should have been settled by a rabbinical court and that the parents' prison sentence was "puzzling." He insisted the Sephardi girls had the right to choose to attend a mixed school.

"Everyone wants to send their children to Ashkenazi schools," said another demonstrator, Zion Harounian, 62, a Sephardic father of nine. "The quality of the Ashkenazi schools is much higher. They are stronger politically, so they get more money."

Israel's ultra-Orthodox minority of some 650,000 Jews -- just under 10 percent of the nation's population -- is an insular community that has been known to riot over the state's intrusion into its affairs. They have been criticized for maintaining a separate, state-funded school system that focuses on religious studies.